Abstract: Objective To investigate the value of serum carbohydrate antigen 19- 9( CA19- 9) and carbohydrate antigen 24- 2( CA24-2) in the diagnosis of benign and malignant biliary tract diseases. Methods A total of 214 patients with biliary tract diseases who were hospitalized in Department of Gastroenterology and Department of General Surgery in the First Hospital Affiliated to Hebei North University from January 2012 to October 2015 were enrolled,and according to the nature of lesions,they were divided into benign lesion group( 162 patients) and malignant lesion group( 52 patients). The healthy people who underwent physical examination during the same period of time in the Physical Examination Center were enrolled as normal control group( 40 persons). Peripheral venous blood was collected for all subjects in a fasting state,and the serum levels of total bilirubin( TBil),direct bilirubin( DBil),and indirect bilirubin( IBil) were measured. Radioimmunoassay was used to measure the serum levels of CA19- 9 and CA24- 2. The Kruskal- Wallis H test was used for comparison of continuous data between multiple groups,and the Wilcoxon rank sum test was used for further comparison between any two groups; the chi-square test was used for comparison of categorical data between groups; Pearson correlation analysis was also performed. Results Compared with the normal control group,the benign lesion group and the malignant lesion group showed significant increases in the serum levels of TBil and CA19- 9( all P < 0. 01). Compared with the benign lesion group,the malignant lesion group showed significant increases in the serum levels of CA19- 9 and CA24- 2( all P < 0. 01). The serum levels of CA19- 9 and CA24- 2 were not associated with tumor location in cholangiocarcinoma,but they were associated with the degree of tumor differentiation( χ2= 6. 860 and 9. 010,all P < 0. 05). The combined measurementof CA 1 9- 9 and CA 2 4- 2 had a sensitivity of 8 8. 5 % and a specificity of 8 2. 1 % in the diagnosis of cholangiocarcinoma,which were significantly higher than the sensitivity and specificity of CA19- 9 or CA24- 2 measurement( all P < 0. 01). In the patients with benign biliary tract diseases and cholangiocarcinoma,serum CA19- 9 was positively correlated with serum TBil( r = 0. 634 and 0. 346,both P < 0. 05),and the benign lesion group had a significantly greater correlation between serum CA19- 9 and serum TBil than the malignant lesion group. Conclusion Combined measurement of CA19- 9 and CA24- 2 has clinical significance in early diagnosis of cholangiocarcinoma.